Exploring effects of rest and exercise on bone healing

Bone reconstruction surgeries can take weeks or even months to heal, and one of the most powerful tools to aid in recovery is rehabilitation through physical exercise. Movement stimulates the growth of bone and vascular cells, helping to repair injuries and accelerate the healing process. However, too much exercise risks damaging the delicate vasculature, creating setbacks that can lengthen recovery times.

Williams and Muhib et al. investigated the effect of varying levels of rehabilitative exercise on bone injury recovery times, using rodents grouped into different cohorts based on exercise level.

Initially, they sought to group the rats based on the distance they ran on a wheel by restricting one group of rats to less wheel time. However, they quickly realized this approach was confounded by the rats themselves.

“Our initial assumption when we started this work was that the amount of local deformation caused by rehabilitation was the most important factor influencing bone healing,” said author Bob Guldberg. “However, by designing an experiment that varied other parameters like distance, duration, rest, and velocity, we discovered that the optimal rehabilitation regime is more complex than just the intensity of local strain.”

Instead, the group focused on other factors, including exercise time and rest duration. They found that a moderate level of exercise interspersed with longer rest periods provided the best healing outcomes.

The authors hope their findings will lead to better guidelines for surgical rehabilitation in humans.

“This work really showed that rehabilitation parameters matter,” said author Kylie Williams. “You need a middle amount of activity paired with longer rest, but the optimal amounts depended on the severity of the bone injury. More work is needed to achieve prescriptive personalized rehabilitation.”

Source: “Subject-specific multivariate modeling for regenerative rehabilitation of bone healing,” by Kylie E. Williams, Farhan Muhib, Ethan Dinh, Kelly E. Leguineche, Auveen Hajarizadeh, J. Walker Rosenthal, Tyler Guyer, Theo Seah, Nick J. Willett, Jeff Weiss, and Robert E. Guldberg, APL Bioengineering (2025). The article can be accessed at https://doi.org/10.1063/5.0273944 .